Storage tank installation

ABSTRACT

A covering for a collecting tub defining an annular channel around an aboveground storage tank intended to hold an inflammable liquid having a predetermined combustion temperature comprises an annular roof consisting of a plastics material which tends to disintegrate rapidly and substantially without formation of a flame at said combustion temperature.

United States Patent 91 Schwarz [111 3,811,598 [451 May 21, 1974 1STORAGE TANK INSTALLATION [75] Inventor: Karl Schwarz, Linz, Austria[73] Assignee: Verelnigte Osterreichische Eisen-und StahlwerkeAktiengesellschaft, Linz,

Austria 22 Filed: Aug. 5, 1971 21 App1.N0.:169 ,174,

[30] Foreign Application Priority Data Sept. 22, 1970 Austria 8541/70 52us. Cl. 220/88 R, 220/18 51 1m.c1.....- B65d'25/00, B65d 25/24 [58]Field of Search....; 220/85 R, 85 s, 85 on,

220/85-P, 88 R 5A,,24 GT, 89 B, 1 B, 18, 26 S, 26 D, 315, DIG. 6

[56] References Cited UNITED STATES PATENTS 2,546,573 3/1951 Wiggins220/26 S 3,669,302 6/1972, Markarian...

7/1957 Staber 9/1957 Wiggins ..-......'220/26 o 986,395 3/1911 King220/23.4 3,687,329 8/1973 Baum.... 220/88 R 1,823,256 9/1931 Clark 220/1B 1,943,191 l/1934 Schwemlein 220/1 B 1,844,961 2/1932 Kramer 220/1 B1,974,034 9/1934 Pelleriti 220/85 S FOREIGN PATENTS OR APPLICATIONS1,806,186 7/1969 Germany 220/18 1,282,344 12/1961 France 220/26 S929,723 6/1963 Great Britain 220/26 S Primary ExaminerWilliam 1. PriceAssistant Examiner-Allan N. Shoap Attorney, Agent, or Firm-Kurt Kelman[5 7] ABSTRACT A covering for a collecting tub defining an annularchannel around an aboveground storage tank intended to hold aninflammable liquid having a predetermined combustion temperaturecomprises an annular roof consisting of a plastics material which tendsto disintegrate rapidly and substantially without formation of a flameat said combustion temperature.

3 Claims, 4 Drawing Figures QATENTEDMAY 21 lHN- 3, 8 I1, 5 9 8 PATENTEMY21 m4 3,811 ,598

- sum 2 0f '2 STORAGE TANK INSTALLATION This invention relates to acovering for annular collecting tubs of high-capacity, abovegroundstorage tanks which hold inflammable liquids, which covering comprisesan annular roof, which preferably terminates over a gutter carried bythe outer wall of the collecting tub.

High-capacity, aboveground storage tanks. which serve to hold petroleumproducts or the like must be surrounded by a protective bank or betterby a collecting tub so that in case of a leakage of the tank or anoverflow of its contents an uncontrolled flow of the escaped liquid anda risk of a contamination of the underground water can be prevented. Thecollecting tubs are often made from steel and have such'a high capacitythat they can hold a large part of or the entire contents of the tank.

inner edge portion extending between two continuous peripheral flangescarried by the wall of the highcapacity storage tank and have ,adownturned outer edge portion having parts which bear on the bottom ofthe gutter. The annular roof can then be formed from prefabricatedplates of plastics material which can easily be made and there is noneed for a special design of the covering to conform to the annularconfiguration of the gutter. Because parts of the downturned outer edgeportion of the plates of plastics material bear on the bottom of thegutter, a special support for the covering 7 is not required. When theplates of plastics material have been placed on the tub, openings areleft between It has been known for a long time to surround suchhigh-capacity tanks with earth banks or protective area so that thefire-fighting equipment can be moved quickly to the source of the fireand the fire can be suppressed with relatively small amounts offireextinguishing foam.

If such collecting troughs are open-topped, any precipitated water canfreely enter the annular collecting channel between the outer wall ofthe tank and the outer wall of the collectingtub and can collect ,inthat space. To avoid such collection of precipitated water, it is knownto provide the collecting tubs with a sheet steel covering and withmeans to conduct the rainwater outwardly. In case of a fire, however,such covering of sheet steel preventsa rapid supply offire-extinguishing foam to the burning surface so that it is verydifficult to extinguish the fire. v Hence. it isan object of theinvention to eliminate these disadvantages and to provide a covering forcollecting tubs defining an annular channel around highthe supportingparts of the plates and enable an equalization of pressure so that anyair flow cannot produce suction. These openings ensure also that anyleakage liquid draining over the roof will enter the interior of thecollecting tub.

To prevent a sagging or bending of relativelylarge plates of plasticsmaterial, radial stiffening ribs are provided on the plates of plasticsmaterial.

An illustrative embodiment of the invention is shown byway of example onthe accompanying drawings, in which I FIG. 1 is a fragmentary verticalsectional view showing a portion of a high-capacity storage tankprovided with a collecting tub and a covering according to theinvention.

FIG. 2 is an enlarged fragmentary top plan view showing a portion of thecovering.

FIG. 3 is an enlarged sectional view taken on line III- III in FIG. 2and capacity storage tanks, which covering prevents an in- I objectessentially in that the roof consists of a plastics material which atthe combustion temperature of the liquid stored in the tank meltsrepidly or burns whereas it is inflammable with difficulty. Hence, thecovering will be destroyed soon after the'outbreakof a fire so that thesurface of the burning liquid is freely accessible andfire-extinguishing foam can be applied quickly and in a simple manner tothe surface of the burning liquid. In accordance with the invention theroof consists of a plastics material which burns but is difficultlyinflammable so-that in case ofa fire there will be no burning roofportions which by the wind created by the fire are carried into the areaaround the fire, which would thus be propagated. At the present time,the plastics material industry is aware of certain admixtures which canbe added to almost all plastics materials concerned so that they burn ina flame whereas the combustion ceases when there is no external sourceof fire.

A simple covering according to the invention will comprise a roofconsisting of overlapping, preferably trapezoidal plates of plasticsmaterial. which havean FIG. 4 is an enlarged sectional view taken online IV-lV of FIG. 2.

A high-capacity, aboveground storage tank 1 for holding combustibleliquid is placed in a collecting tub 2 having a sheet steel bottom 2 anda sheet steel outer wall 3. The channel between the outer wall 4 of'thetank and the outer wall 3 of the collecting tub is covered by a roof 5,which terminates over a gutter 6 carried by the outer wall 3 ofthecollecting tub. The gutter 6 is provided with a plurality of U-shapeddrainpipes 7 regularly spaced around its periphery. The drainpipes 7have outlet openings which are disposed outside the outer wall 3 of thetub and below the overflow rim of the inner wall of the gutter so a poolof water will always be left in the gutter 6 and the drainpipes 7 willbe filled with water. A sight glass may be inserted in the drainpipes 7.Any water flowing from the roof 5 will enter the gutter6 and will drainoutwardly through the drainpipes 7.. Liquid which has flown over fromthe tank 1 or leakage liquid emerging from the high capacity tanks 1through any leaks disposed above the roof 5 will also be conducted intothe gutter 6 from the roof but as these liquids are in most caseslighter than water they will flow over the inner wall of the gutter intothe collecting tub.

The roof 5 consists of overlapping trapezoidal plates 8 of plasticsmaterial. The inner edge portions of these plates extend betweenperipheral flanges 9 provided on the wall 4 of the high-capacity storagetank. Parts of the downturned outer edgeportions of the plates 8 bear onthe bottom of the gutter. Radial stiffening ribs 11 are provided toprevent a bending or sagging of the plates 8 of plastics material.

When a fire has broken out, the plates 8 of plastics material melt orburn without forming a flame, e.g., at

a temperature of 150 C. so that the covering is destroyed and thesurface of the burning liquid is exposed to receive thefire-extinguishing foam.

What is claimed is:

1. In a storage tank installation which comprises a collecting tubhaving an outer wall, a gutter carried by the outer tub wall, the gutterhaving a bottom, an above-ground storage tank for an inflammable liquidhaving a predetermined combustion temperature, the tank having an outerwall and being placed into the tub, the outer tub wall and the outertank wall being spaced from each other to define an annular chamberaround the tank for collecting therein any of the inflammable liquidcoming from the tank, and a covering for the annular collecting chamberof the tub, the covering consisting ofa rigid annular roof having aninner edge adja- 2. An installation as set forth in claim 1, in whichsaid plates are trapezoidal.

3. An installation as set forth in claim 1, in which said plates areprovided with radial stiffening ribs.

1. In a storage tank installation which comprises a collecting tubhaving an outer wall, a gutter carried by the outer tub wall, the gutterhaving a bottom, an above-ground storage tank for an inflammable liquidhaving a predetermined combustion temperature, the tank having an outerwall and being placed into the tub, the outer tub wall and the outertank wall being spaced from each other to define an annular chamberaround the tank for collecting therein any of the inflammable liquidcoming from the tank, and a covering for the annular collecting chamberof the tub, the covering consisting of a rigid annular roof having aninner edge adjacent the outer tank wall and an outer edge disposed overthe gutter:
 1. the roof consisting of overlapping plates of a plasticsmaterial disintegrating rapidly and without flame formation at saidcombustion temperature,
 2. two vertically spaced apart, peripheralflanges affixed to the outer tank wall, and
 3. the roof plates having aninner edge extending between the flanges and a downturned outer edgeportion having parts bearing on the gutter bottom.
 2. two verticallyspaced apart, peripheral flanges affixed to the outer tank wall, and 2.An installation as set forth in claim 1, in which said plates aretrapezoidal.
 3. An installation as set forth in claim 1, in which saidplates are provided with radial stiffening ribs.
 3. the roof plateshaving an inner edge extending between the flanges and a downturnedouter edge portion having parts bearing on the gutter bottom.